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Full text of "The Morphology And Evolution Of The Apes And Man"

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THE  JOINTS                            157
the joint in the Chimpanzee is applicable to that of she other Anthropoids. The external lateral ligament is as in Man, but the internal lateral ligament is fixed to the upper part of the internal surface of the shaft of the tibia. The oblique popliteal ligament is absent, but is replaced by a strong femoral intercondylar cord connecting the sesamoid bones which give origin to ihe heads of the gastrocnemius. Keith (96) points out that the oblique ligament terminates above in this cord. The anterior cruciate ligament is attached to the tibia as in Man, and its femoral attachment is to the upper half of the mesial aspect of the external condyle. The posterior cruciate ligament is attached to the tibia farther back than in Man, and it receives a slip from the external semilunar cartilage. The ligamentum mucosum is as in Man. The internal semilunar cartilage is large and crescentic; it is attached in front of the anterior cruciate ligament, and its posterior attachment is as in Man. The external semilunar cartilage forms a small, complete circle. Internallv it is attached to the outer side of the
tubercles and spine of the tibia. Postero-mesially it is attached to the outer surface of the internal condyle of the femur, and it is connected to the posterior cruciate ligament. Humphry (340) pointed out that the femur in Man is broad and comparatively flat on the distal end of the external condyle, and the lateral ligaments are attached nearer the posterior parts of the bone; so the joint is firm and locked when it is fully extended. Moreover, when the joint is fully extended the lateral, cruciate and posterior ligaments are tight. In the Chimpanzee the distal end of the external condyle of the femur is rounded, the external ligament is not attached far back,